Impact wrench

ABSTRACT

An impact wrench for use in tightening or loosening threaded parts, the wrench including a spindle adapted to engage a nut or bolt, a moment arm porjecting transversely of the spindle, a semicircular brace disposed radially of the spindle and interconnected at its ends to the ends of the moment arm, and a breaker bar pivotally secured on the spindle and adapted to impart a force substantially simultaneously to the moment arm at both ends thereof thus applying a uniform and balanced application of torque to the workpiece.

United States Patent 1191 Miller Aug 27, 1974 IMPACT WRENCH [76]Inventor: Robert G. Miller, 311 w. Prairie sr, Examme-'j?mes Jones CampPoint, L 62320 Attorney, Agent, or Firm-Henderson & Strom [22] Filed:July 13, 1972 57 A S C I [21] Appl. No.: 271,505 An impact wrench foruse in tightening or loosening threaded parts, the wrench including aspindle [52] U S C] 81/52 3 adapted to engage a nut or bolt, a momentarm por- [511 In} .0 19/60 j g transversely of the Spindle, asemicircular I brace disposed radially of the spindle and intercom [58]Field of Search 81/523, 173/93 nected at its ends to the ends of themoment arm, and a breaker bar pivotally secured on the spindle and [56]gFXF Sg adaptedto impart a force substantially simultaneously to themoment arm at both ends thereof thus applying 1i; gaird a uniform andbalanced application of torque to the arnson 3,145,593 8/1964 Humphrey173 93 workpece' 3,158,050 11/1964 Shandez 81/523 x 1 Claim, 6 DrawingFigures IMPACT WRENCH BACKGROUND OF THE INVENTION The loosening ortightening of screw threadedparts may either be accomplished by applyinga constant twisting force, or by applying an instantaneous impact force.The advantage of applying an impact force isreadily manifest in theseparation of screw threaded parts which will not yield to an instanttorque and in situations where the torque requirements are greater thancan normally be applied. In many instances threaded parts are assembledwith power assisted tools or freeze because of rust or other foreignmaterial imbedded between the threads of the corresponding parts.Furthermore, many such parts must be assembled or reassembled to a hightorque to assure safe operation ofthe parts in their subsequent use.often the necessary power tools are unavailable or excessivelyexpensive.

A number of impact wrenches have been manufactured, however, they arenot effective in use. One such wrench has a spindle adapted to receive asocket and having an arm projecting radially thereof. A bar is rotatablymounted on the spindle and projects radially thereof and a weight isdisposed on the free end of the bar. An arm also is secured to the barand also projects radially thereof, wherein, upon grasping the weightand imparting a force thereto the bar strikes the arm and provides atorque to the socket through the spindle. Unfortunately not only is atorque applied but also a resultant force is applied, which is generallyangularly disposed to the axis of the socket. This resultant force canand does strip the faces of the bolt or nut, leaving the operator in aposition wherein the bolt or nut must be cut from its mating part.

One wrench, U.S. Pat. No. 3,158,050, attempted to provide an arm whichprojected radially from both sides of the spindle and a bar whichprojected beyond ,both ends of the arm. Lugs were secured to the armwherein rotation of the bar coacted with both lugs to eliminate theresultant force discussed hereinabove. Warping of the bar or damage toone of the lugs, however, defeats the object thereof and a resultantforce will occur. Again that wrench having a securing device mounted tothe spindle outwardly of the socket to provide stability to the spindlefor lessening the possibility of causing a resultant force when the barstrikes the lugs. It will be obvious that care must be taken to pre ventdamage to the lugs or the breaker bar. Furthermore, as the bar projectsradially outwardly of the spindle considerablly more space is requiredto effectively use the wrench.

SUMMARY OF THE INVENTION This invention relates to an impact wrench andmore particularly to a manually operated tool wherein the inertia of aweighted pivotally mounted breaker bar in combination with a moment armsecured to a spindle is utilized to loosen or tighten threaded parts,and wherein the inertia of the bar is converted into a torque whichcoacts on opposed sides of the spindle through a brace elementinterconnected between both ends of the moment arm, thus substantiallyeliminating any resultant forces.

The impact wrench includes a spindle adapted to axially receive a socketon one end thereof and having a handle joumalled to the other endthereof. Secured, intermediate the ends of the spindle, is a radiallyprojecting trough shaped moment an'n which extends outwardly an equaldistance on opposed sidesof the spindle. Disposed in each end of thetrough is a boss which projects normally thereto. A semicircular braceinterconnects the ends of the arm-on the side opposite the bosses. Anarcuate shaped brace is secured to the arm inside the semicircular braceand vertically disposed links interconnect the braces to the armintermediate their respective ends. A second substantially semicircularoffset holding unit is secured to the sides of the ends of the arm andprojects oppositely to the braces and includes holding spurs foradditional sockets. Pivotally connected to the spindle in the plane ofthe'braces is a weighted breaker arm which will pivot about the spindleto contact the bosses.

It is an object of this invention to provide an impact wrench which willapply a torque to a socket but which does not provide any angularlydisposed resultant force.

Another object of this invention is the provision of an impact wrenchhaving a breakerbar which is pivotally connected at one end to thespindle but which applies a substantially equal force to opposed sidesof the spindle through a brace secured to opposite ends of a moment armwhich is secured transversely to the spindle.

A further object of the inventionis to provide an impact wrench whichhas a holding unit for sockets, thus eliminating separate storage unitsfor parts.

Yet another object of this invention is the provision of an impactwrench which is durable of construction, extremely effective inoperation and uncomplicated in manufacture.

These objects and other featuresandiadvantages be come more readilyapparent upon reference to the'following description when taken inconjunction with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of theimpact wrench of this invention in combination with a wheel and itscomponent lugs or nuts, thus showing one area of its operation;

FIG. 2 is a top plan view thereof;

FIG. 3 is a side elevational view thereof, wherein the opposite side isa mirror image thereof;

' DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings,the impact wrench of this invention is indicated generally at 10 inFIGS. 1 6, and is depicted in use in a typical application. The wrench10 (FIG. 1) is operably mounted on a lug or nut 11 which secures a wheel12, having a tire 13 mounted thereon, to an axle (not shown) or thelike. The lug or nut 11 is threadably mated with a correspondingthreaded part (not shown) and although this description specificallydiscloses an application related to the removal of a wheel from an axleit is not intended to so limit same as its application is universallyapplicable to dle 14, a handle 18 journalled to the other end 18 of thespindle 14, a moment arm 19 secured to the spindle 14 intermediate itsends and projecting transversely thereto, a brace unit 21 secured at itsends to the ends of the moment arm 19, a breaker bar 22 pivotallysecured to the spindle 14 at the intersection of the spindle 14 and thearm 19, and a holding unit 23 secured to the arm 19 opposite the braceunit 21 for holding additional sockets 16 in storage.

Referring now to FIGS. 2 and 3, the spindle 14 is depicted as anelongated rod which has a turned down section 24 intermediate its ends17 and 18. Detachably mounted on the one end 17 is a socket 16 adaptedto engage the head of a lug or bolt, or a nut in mating relationship.

Journalled to the other end 18 in a conventional manner is a handle 17,thus permitting an operator to securely hold the handle to support thewrench in a proper plane against the work piece, nut or lug, when thespindle rotates.

The moment arm 19 (FIGS. 2 and 6) is formed from an elongated memberwhich is trough shaped 26 in cross section. Upstanding bosses 27 and 28are integrally disposed in each end, 29 and 31, respectively, of thetrough 26 and a cutout 32 is formed in the trough 26 intermediate itsends. The moment arm 19 is secured to the spindle proximate the turnedsection 24 with section 24 disposed in the trough 26 over the cutout 32,with the opposed ends 29 and 31 projecting radially of the spindle l9.

Secured to and depending from the moment arm 19 is the brace unit 21(FIGS. and 6). The brace unit 21 comprises a semicircular brace 33connected at its end 34 and 36 to the underside of the trough 26opposite the bosses 27 and 28. Proximate the spindle cutout 32 areparallel links 37 and 38 which interconnects the trough 26 to thesemicircular brace 32 thus preventing the latter from turning ortwisting from a plane normal to the axis of the spindle 29 and trough26. Disposed between the trough 26 and the semicircular brace 33 is anarcuate shaped brace 39 which is secured at its ends 41 and 42 to thetrough 26 inwardly of the ends 34 and 36 and to the links 37 and 38 atits intersection therewith. The arcuate brace 39 also assists inpreventing the semicircular brace 33 from twisting or turning.

Pivotally secured to the spindle 19 at the turned section 24 (FIGS. 3and 5) and within the trough 26 is the breaker bar 22. The bar one end41 is journalled on the turned section 24 and a weight 41 is integrallymounted on the bar other end 42. It will be noted in FIG. 5 that the barcontacts the moment arm 19 only at the bosses 27 and 28 when it is swungeither to the right or left.

The holding unit 23 (FIGS. 1 and 5) comprises a semicircular element 43connected intermediate its ends 47 and 48 to one end 44 of a leg 46 andat its ends 47 and 48 to the semicircular brace ends 34 and 36 and themoment arm ends. Approximately intermediate the leg 46 and the elementends 47 and 48 are a pair of opposed socket holding arms 49 and 51. Eacharm has its free end threaded to receive a wing nut 52. Slidablydisposed on the holding arms 49 and 51 are sockets 16 (FIG. I). Theother end 53 of the leg 46 is secured to the spindle 14 adjacent to andoutside the moment arm 19, thus it will be seen that the plane of theelement 43 is offset from the plane of the brace unit 21.

In operation a socket having the appropriate inside dimensions isselected from the supply of same on the holding arms 49 and 51 andmounted on the spindle one end 17. The socket then is disposed over thelug or nut 16 which is to be loosened or tightened. The spindle isgrasped at the handle 17 with the axis of the spindle aligned with theaxis of the nut or lug. The weight is grasped and thrown to the right orleft (FIG. 5) to tighten or loosen the nut. The impact of the bar 22against the boss 28 will be transmitted through the moment arm to thespindle and through the semicircular brace 33 to the other end of themoment arm and then to the spindle thus applying opposed forces to thespindle, and providing an impact torque to the nut or lug. As the handleis journalled to the spindle a minimum effort is required to hold thewrench in proper alignment even when the breaker bar is pivoted ineither direction. The extra sockets are always available thuseliminating the need for extra storage equipment. But more importantlythe impact torque will have no resultant force to cause the socket todamage the head of the lug or the faces of the nut.

I claim:

1. An impact wrench for tightening and loosening screw threaded parts,the wrench comprising:

a spindle having a socket mounted on one end thereof and a handlejournalled to the other end thereof in axial alignment with the spindle;

a moment arm secured at its midpoint to said spindle and projectingtransversely thereof, said moment arm being an elongated member which istrough shaped in cross section and having a boss integrally disposed oneach end thereof which projects upwardly into the trough; firstsemicircular bar-shaped brace secured at its ends to said moment armends and lying in a plane normal to the axis of said spindle; breakerbar means pivotally mounted on one end to said spindle and having anintegral weight secured to its other end, for applying an impact forceto said moment arm, said breaker bar being disposed radially of saidspindle and operable in the plane of said brace;

a second semicircular bar-shaped holding unit brace secured at its endsto said moment arm ends, said second semicircular brace lying in a planewhich is different from the plane in which the first semicircular bracelies;

two inwardly projecting socket holding means for detachably holding asocket which is not being used, said two socket holding means beingsymmetrically disposed on said second semicircular brace wherein eachsocket holding means includes mating threaded members;

a third arcuate bar-shaped brace having its ends secured to said momentarm and lying in the same plane as said first semicircular brace;

a first link member extending from one side of said moment arm to anintermediate portion of said first semicircular brace and connected tosaid third arcuate brace; I

a second link member extending from the other side of said moment arm toan intermediate portion of said first semicircular brace and connectedto said third arcuate brace; and

a third link member extending from the middle of said moment arm to themidpoint of said second semicircular brace.

1. An impact wrench for tighTening and loosening screw threaded parts,the wrench comprising: a spindle having a socket mounted on one endthereof and a handle journalled to the other end thereof in axialalignment with the spindle; a moment arm secured at its midpoint to saidspindle and projecting transversely thereof, said moment arm being anelongated member which is trough shaped in cross section and having aboss integrally disposed on each end thereof which projects upwardlyinto the trough; a first semicircular bar-shaped brace secured at itsends to said moment arm ends and lying in a plane normal to the axis ofsaid spindle; a breaker bar means pivotally mounted on one end to saidspindle and having an integral weight secured to its other end, forapplying an impact force to said moment arm, said breaker bar beingdisposed radially of said spindle and operable in the plane of saidbrace; a second semicircular bar-shaped holding unit brace secured atits ends to said moment arm ends, said second semicircular brace lyingin a plane which is different from the plane in which the firstsemicircular brace lies; two inwardly projecting socket holding meansfor detachably holding a socket which is not being used, said two socketholding means being symmetrically disposed on said second semicircularbrace wherein each socket holding means includes mating threadedmembers; a third arcuate bar-shaped brace having its ends secured tosaid moment arm and lying in the same plane as said first semicircularbrace; a first link member extending from one side of said moment arm toan intermediate portion of said first semicircular brace and connectedto said third arcuate brace; a second link member extending from theother side of said moment arm to an intermediate portion of said firstsemicircular brace and connected to said third arcuate brace; and athird link member extending from the middle of said moment arm to themidpoint of said second semicircular brace.